fix(fetch): await response listener before resolving the response pro…

…mise (#658)

Co-authored-by: Artem Zakharchenko <[email protected]>

src/interceptors/fetch/index.ts

@@ -144,15 +144,15 @@ export class FetchInterceptor extends Interceptor<HttpRequestEventMap> {
         'no mocked response received, performing request as-is...'
       )
 
-      return pureFetch(request).then((response) => {
+      return pureFetch(request).then(async (response) => {
         this.logger.info('original fetch performed', response)
 
         if (this.emitter.listenerCount('response') > 0) {
           this.logger.info('emitting the "response" event...')
 
           const responseClone = response.clone()
 
-          this.emitter.emit('response', {
+          await emitAsync(this.emitter, 'response', {
             response: responseClone,
             isMockedResponse: false,
             request,

test/modules/fetch/response/fetch-await-response-event.test.ts

@@ -0,0 +1,68 @@
+// @vitest-environment node
+import { vi, it, expect, beforeAll, afterAll, afterEach } from 'vitest'
+import { HttpServer } from '@open-draft/test-server/http'
+import { FetchInterceptor } from '../../../../src/interceptors/fetch'
+
+const httpServer = new HttpServer((app) => {
+  app.get('/resource', (req, res) => {
+    res.send('original response')
+  })
+})
+
+const interceptor = new FetchInterceptor()
+
+beforeAll(async () => {
+  interceptor.apply()
+  await httpServer.listen()
+})
+
+afterEach(() => {
+  interceptor.removeAllListeners()
+})
+
+afterAll(async () => {
+  interceptor.dispose()
+  await httpServer.close()
+})
+
+it('awaits response listener promise before resolving the mocked response promise', async () => {
+  const markStep = vi.fn<[number]>()
+
+  interceptor.on('request', ({ controller }) => {
+    controller.respondWith(new Response('hello world'))
+  })
+
+  interceptor.on('response', async ({ response }) => {
+    markStep(2)
+    await response.text()
+    markStep(3)
+  })
+
+  markStep(1)
+  await fetch('http://localhost/')
+  markStep(4)
+
+  expect(markStep).toHaveBeenNthCalledWith(1, 1)
+  expect(markStep).toHaveBeenNthCalledWith(2, 2)
+  expect(markStep).toHaveBeenNthCalledWith(3, 3)
+  expect(markStep).toHaveBeenNthCalledWith(4, 4)
+})
+
+it('awaits response listener promise before resolving the original response promise', async () => {
+  const markStep = vi.fn<[number]>()
+
+  interceptor.on('response', async ({ response }) => {
+    markStep(2)
+    await response.text()
+    markStep(3)
+  })
+
+  markStep(1)
+  await fetch(httpServer.http.url('/resource'))
+  markStep(4)
+
+  expect(markStep).toHaveBeenNthCalledWith(1, 1)
+  expect(markStep).toHaveBeenNthCalledWith(2, 2)
+  expect(markStep).toHaveBeenNthCalledWith(3, 3)
+  expect(markStep).toHaveBeenNthCalledWith(4, 4)
+})

test/modules/http/response/http-await-response-event.test.ts

@@ -2,7 +2,7 @@ import { vi, it, expect, beforeAll, afterAll, afterEach } from 'vitest'
 import http from 'node:http'
 import { HttpServer } from '@open-draft/test-server/http'
 import { ClientRequestInterceptor } from '../../../../src/interceptors/ClientRequest'
-import { sleep, waitForClientRequest } from '../../../helpers'
+import { waitForClientRequest } from '../../../helpers'
 
 const httpServer = new HttpServer((app) => {
   app.get('/resource', (req, res) => {
@@ -27,35 +27,49 @@ afterAll(async () => {
 })
 
 it('awaits asynchronous response event listener for a mocked response', async () => {
+  const markStep = vi.fn<[number]>()
+
   interceptor.on('request', ({ controller }) => {
     controller.respondWith(new Response('hello world'))
   })
 
-  const responseDone = vi.fn()
   interceptor.on('response', async ({ response }) => {
-    await sleep(200)
-    const text = await response.text()
-    responseDone(text)
+    markStep(2)
+    await response.text()
+    markStep(3)
   })
 
+  markStep(1)
   const request = http.get('http://localhost/')
   const { text } = await waitForClientRequest(request)
+  markStep(4)
 
   expect(await text()).toBe('hello world')
-  expect(responseDone).toHaveBeenCalledWith('hello world')
+
+  expect(markStep).toHaveBeenNthCalledWith(1, 1)
+  expect(markStep).toHaveBeenNthCalledWith(2, 2)
+  expect(markStep).toHaveBeenNthCalledWith(3, 3)
+  expect(markStep).toHaveBeenNthCalledWith(4, 4)
 })
 
 it('awaits asynchronous response event listener for the original response', async () => {
-  const responseDone = vi.fn()
+  const markStep = vi.fn<[number]>()
+
   interceptor.on('response', async ({ response }) => {
-    await sleep(200)
-    const text = await response.text()
-    responseDone(text)
+    markStep(2)
+    await response.text()
+    markStep(3)
   })
 
+  markStep(1)
   const request = http.get(httpServer.http.url('/resource'))
   const { text } = await waitForClientRequest(request)
+  markStep(4)
 
   expect(await text()).toBe('original response')
-  expect(responseDone).toHaveBeenCalledWith('original response')
+
+  expect(markStep).toHaveBeenNthCalledWith(1, 1)
+  expect(markStep).toHaveBeenNthCalledWith(2, 2)
+  expect(markStep).toHaveBeenNthCalledWith(3, 3)
+  expect(markStep).toHaveBeenNthCalledWith(4, 4)
 })